Photoconductive detectors made of mercury cadmium telluride semiconductor material are disclosed in U.S. Pat. No. 3,949,223, issued Apr. 6, 1976, and entitled, "Monolithic Photoconductive Detector Array." The '223 patent also discloses several methods for making such detectors, but none of these methods produces a detector that operates close to the theoretical maximum detectivity for wavelengths in the range of about 1 to about 25 microns, particularly for wavelengths in the range of about 10 to about 25 microns, and more particularly where such radiation appears in low background levels such as those having less than about 10.sup.17 photons/ cm.sup.2 -sec.
A concurrently-filed, commonly assigned U.S. application entitled, "Photoconductive Detectors and Methods of Making Such Detectors," describes other processes for making photodetectors of the kinds disclosed hereinbelow.